docs: fix and add missing natspecs

Author: MerlinEgalite

src/wsteth-exchange-rate-adapter/WstEthStEthExchangeRateChainlinkAdapter.sol

@@ -8,12 +8,18 @@ import {MinimalAggregatorV3Interface} from "./interfaces/MinimalAggregatorV3Inte
 /// @author Morpho Labs
 /// @custom:contact security@morpho.org
 /// @notice wstETH/stETH exchange rate price feed.
-/// @dev This contract should only be used as price feed for `ChainlinkOracle`.
+/// @dev This contract should only be used as price feed for `MorphoChainlinkOracleV2`.
 contract WstEthStEthExchangeRateChainlinkAdapter is MinimalAggregatorV3Interface {
+    /// @inheritdoc MinimalAggregatorV3Interface
     uint8 public constant decimals = 18;
+
+    /// @notice The description of the price feed.
     string public constant description = "wstETH/stETH exchange rate";
+
+    /// @notice The address of stETH on Mainnet.
     IStEth public constant ST_ETH = IStEth(0xae7ab96520DE3A18E5e111B5EaAb095312D7fE84);
 
+    /// @inheritdoc MinimalAggregatorV3Interface
     /// @dev Silently overflows if `getPooledEthByShares`'s return value is greater than `type(int256).max`.
     function latestRoundData() external view returns (uint80, int256, uint256, uint256, uint80) {
         // It is assumed that `getPooledEthByShares` returns a price with 18 decimals precision.

src/wsteth-exchange-rate-adapter/interfaces/MinimalAggregatorV3Interface.sol

@@ -3,9 +3,13 @@ pragma solidity >=0.5.0;
 
 /// @dev Inspired by
 /// https://github.com/smartcontractkit/chainlink/blob/master/contracts/src/v0.8/shared/interfaces/AggregatorV3Interface.sol
+/// @dev This is the minimal feed interface required by `MorphoChainlinkOracleV2`.
 interface MinimalAggregatorV3Interface {
+    /// @notice Returns the number of decimals precision.
     function decimals() external view returns (uint8);
 
+    /// @notice Returns Chainlink's `latestRoundData` return values.
+    /// @notice Only the `answer` field is used by `MorphoChainlinkOracleV2`.
     function latestRoundData()
         external
         view